(1) Field of the Invention
The present invention relates to a scheduling method and program for a substrate processing apparatus that performs predetermined processes on semiconductor wafers or glass substrates for liquid crystal displays (which will be referred to hereinafter simply as substrates).
(2) Description of the Related Art
Conventionally, little power-saving effort has been made with this type of substrate processing apparatus. The apparatus has an electrical feature designed by taking into consideration a possibility of simultaneously operating all power-consuming components.
However, where the apparatus includes a plurality of heaters that consume a relatively large quantity of electricity, power consumption is reduced by prohibiting a simultaneous use of such heaters and exclusively using each heater by successively switching from one heater to another.
The conventional practice noted above has the following drawbacks.
The exclusive control is carried out though occasionally a margin may be allowed for power consumption. Thus, extended periods of time may be needed for increasing temperature by the heaters. This results in a problem of lowering the use efficiency of a resource such as a chemical processing unit.
The apparatus uses not only electric power but other consumer items, such as deionized water, chemical solution and gas, that have fixed maximum quantities available per unit time. Where these items are supplied to a plurality of locations, consumption per unit time is reduced, again, by exclusively supplying the items. Thus, a problem similar to that relating to electric power arises also with deionized water, chemical solution and gas.
Further, as opposed to the consumption noted above, waste fluids discharged from the apparatus, including waste liquids such as a treating solution and deionized water and an exhaust gas such as nitrogen gas, are transmitted to waste treating equipment having a fixed disposal capacity per unit time. Thus, an exclusive control must be carried out for resources that discharge wastes, so that the wastes are discharged at rates not exceeding the disposal capacity. This poses a problem of lowering the use efficiency of the resources also.
The present invention has been made having regard to the state of the art noted above, and its object is to provide a scheduling method and program for a substrate processing apparatus, in which a capacity resource is used by taking an expected use of a consumer item into account, thereby making efficient use of resources while controlling the resources not to exceed maximum consumption.
Another object of the invention is to provide a scheduling method and program for a substrate processing apparatus, in which a capacity resource is used by taking an expected discharge of a waste into account, thereby making efficient use of resources while controlling the resources not to exceed a maximum discharge rate.
The above objects are fulfilled, according to the present invention, by a method of preparing a schedule for a substrate processing apparatus having a plurality of resources for processing substrates, the schedule determining timing of using each resource for processing the substrates, the method comprising the steps of determining the timing of using each resource in advance of starting an processing of the substrates, defining a capacity resource as a resource usable within a maximum quantity of consumption of a consumer item used by the resources, and using the resources in processing the substrates while avoiding a total quantity of the consumer item used by the resources exceeding the maximum quantity of consumption of the capacity resource.
In determining use timing of each resource before a processing operation, a total of the consumer item is prevented from exceeding the maximum consumption of the capacity resource. In this way, the resources are used efficiently while effecting controls not to exceed the maximum consumption. As a result, the substrate processing apparatus achieves improved throughput.
The resources in the present invention include, for example, a substrate transport mechanism that uses electric power in time of movement, a deionized water cleaning unit that uses electric power as well as deionized water and nitrogen gas, a warm water unit that uses electric power to increase temperature, a chemical processing unit that uses a chemical solution such as of sulfuric acid or hydrogen peroxide and electric power, and a heating unit that uses electric power for heating.
It is preferred that the capacity resource determines total consumption per unit time each time the resources are used, and when the total consumption exceeds the maximum consumption, avoids use of one of the resources responsible for an excess part of the total consumption.
Total consumption per unit time by all the resources used simultaneously is determined. When this total exceeds the maximum consumption of the capacity resource, the use of the resource responsible for the excessive consumption is avoided to maintain the maximum consumption. Thus, the total of the consumer item consumed by all the resources used simultaneously is held within the maximum consumption of the capacity resource.
In another aspect of the invention, there is provided a method of preparing a schedule for a substrate processing apparatus having a plurality of resources for processing substrates, the schedule determining timing of using each resource for processing the substrates, the method comprising the steps of determining the timing of using each resource in advance of starting an processing of the substrates, defining a capacity resource as a resource usable within a maximum quantity of a waste discharged from the resources, and using the resources in processing the substrates while avoiding a total quantity of the waste discharged from the resources exceeding the maximum quantity of discharge of the capacity resource.
In determining use timing of each resource before a processing operation, a total of the waste is prevented from exceeding the maximum discharge of the capacity resource. In this way, the resources are used efficiently while effecting controls not to exceed the maximum discharge. As a result, the substrate processing apparatus provides improved throughput.
The resources in the present invention include, for example, a deionized water cleaning unit that discharges used deionized water and nitrogen gas, a chemical processing unit that discharges a used chemical solution and a drying unit that discharges used nitrogen gas.